1. Field of the Invention
The present invention relates to a light-guiding module. In particularly the present invention relates to combine a reflection unit with a light-guiding plate.
2. Description of Related Art
A backlight module uses as a backlight source, and is applied broadly to various information, communication and consumer products, such as LCDs, film scanners, filmstrips or overhead projectors. The LCD field is the main application of the backlight module and has flourished recently, so that the components of the backlight module are becoming more and more important. How to reduce the cost of materials, shorten the time needed for assembly, improve manufacturing efficiency, increase the lighting uniformity, and increase the illumination are the main issues that need to be solved in this field.
The backlight module comprises a light source, a light-guiding plate, a reflection sheet, a diffusion sheet, a prism sheet (or a brightness enhancement film) and so on. The principle of the backlight module can be described simply as a spontaneous light source, for example a CCFL or LEDs, is guided by the light-guiding plate, then to generate a large, evenly and brightly illuminated surface, the reflection sheet reflects the light scattered therefrom to the illuminated surface. The advantages of the backlight module comprise: its weight is light, the illumination is high, the viewing angle is excellent, the efficiency of light-utilizing is high, and its structure is simple. In general, during the backlight module assembly process, the spontaneous light source faces to the light-guiding plate. The other surfaces of the light-guiding plate are pasted with reflection sheets except for the illumination surface, which are provided to reflect the light at the bottom and the edge of the light-guiding plate in order to improve the lighting efficiency. A light-guiding module is composed of the light source, a light-guiding plate and reflection sheets.
Reference is made to FIGS. 1 and 2, a light-guiding module of the prior art comprises a light-guiding plate, a LED module 2a disposed at one side of the light-guiding plate 1a, a CCFL 4a arranged opposite to the LED module 2a, and a reflection sheet 3a pasted on a bottom surface of the light-guiding plate 1a. The reflection sheet 3a extends from the bottom surface of the light-guiding plate 1a to the side surfaces of the light-guiding plate 1a and wraps the light-guiding plate 1a. The backlight module is composed by the light-guiding module of the prior art, diffusion sheet, etc. The LED module 2a comprises a printed circuit board (PCB) 20a and a plurality of LEDs 21a disposed on the PCB 20a. In order to prevent PCB 20a from absorbing the light emitting from the LEDs 21a (it depends on the material of the PCB20a and the reflection rate), a reflection sheet 22a is pasted on the PCB 20a and faces to the light-guiding plate 1a before the LED module 2a is assembled to the light-guiding plate 1a. Therefore, light absorbed by the PCB 20a can be diminished.
The conventional method of manufacturing a light-guiding module has three major drawbacks that the present invention seeks to overcome. Firstly, the step of pasting the reflection sheet 22a is performed before the LED lighting module 2a is assembled together with the light-guiding plate 1a. Moreover, the reflection sheet 22a must accurately cover the printed circuit board 20a. Regardless of the design or the quantity of the reflection sheet 3a, the total assembly process comprises at least twice step of pasting the reflection sheet, once by the reflection sheet 22a and another by the reflection sheet 3a. These two steps are not finished continuously. Due to the complex design of the reflection sheet 3a and the reflection sheet 22a provided, far more time and labor are required in the assembly process.
Furthermore, if we want the reflection sheet 3a to steadily wrap the light-guiding plate 1a, then an adhesive must be smeared over the reflection sheet 3a. However, this wastes a lot of time, and, furthermore, the adhesive impedes illumination, causing a further decrease in the lighting uniformity of the light-guiding plate 1a. What is more, the illumination of the light-guiding plate 1 a is also decreased because of the reflection sheet 3a absorbs the light.
The third drawback of the conventional method is the complex nature of the assembly process. Initially a diffusion sheet and a frame are joined together. Then the light-guiding module must be stacked upon a frame to form a module-to-be. Finally, the module-to-be is turned around and placed in a metal frame to form a conventional backlighting module. In practice, this method is highly complex and inconvenient, requiring an unnecessarily long assembly time and thereby adding to production costs.